Safety device for elevators



Aug. 30, 1927. 73

M. SCHElNFELD V AFETY DEVICE FOR ELEVATORS Filed Sept. 4, 1926 SERIES E D SHUNT FIELD Indefzior: V Mrrw Schezgfeld;

flitorneg uoRnrsscHEINrELn, or PHILADELPHIA,

. 1. 4 1 PATENT OFFICE.

PENNSYLVANIA, ASSIGNOR OF ONE-HALF Jro nooB FRIEDMAN, or PHILADELPHIA, PENNSYLVANIA.

1 SAFETY DEVICE FOR ELEVATORS.

Application filed September 4, 1926. Serial No. 133,648.

Myinvention relates to safety devices for elevators, and it has particular relation to means for preventing the starting of elec trically operated elevators in the event that 5 the same are overloaded.

The principal object of my invention is to provide a safety device for electrically operated elevators which is so constructed and arranged as to prevent the starting of the elevator motor in the event that the elevator car-'is overloaded. Afurther object of my invention is to provide in such a device means. for rendering the same inoperative under certain conditions, whereby the normal operation of the motor will not be interfered with by inertia effects when the elevator is carrying a load near to the maximum. A further object of my invention is to provide in such a device means for preventing startingof the motor in the event that the car having been overloaded and the load thereafter is reduced below the maximum while the controlling switch is left in the operatin position. I

he nature and characteristic features of my invention will be more fully understood from the following description, taken in con-c nection with the accompanying drawing forming part hereof, wherein there is shown diagrammatically one form or embodimentof my invention.

In the drawings, the invention is shown as embodied in a device applied to an elevator operated by an electric motor supplied with current from a two wire direct current system, although it will of course be understood that the invention is equally applicable in connection with various other systems of electric power distribution.

Referring to the drawings, 1 is an elevator'car of any preferred construction. Associated with the top beam 2 of the elevator car is an inverted U-shaped suspending bolt 3, connected to the operating cable 4 in any preferred manner. Secured at the lower end-of the depending arms of the U-shaped bolt 3 is a plate 5, secured inplace by means of nuts 6 which are threaded on the arms of the U-shaped bolt 3. Interposed between the plate 5 and the underside of the top beam 2 of the elevator car are heavy springs 7, which are .adapted to be compressed according to the load carried by the car.

Contact pins 8 and 9 are carried by the top beam of the car, and these contact pins 8 and 9 are adapted to be engaged by a contact plate 10 which is supported from the plate 5 by means of a bolt 11, which also serves as a means of adjustment of the position' of the plate 10 with respect to the plate 5. The foregoing arrangement is such that when a predetermined load is placed in the elevator car, the springs 7 will be compressed sufliciently to cause the plate'lO to encounter the contact pins 8 and 9, and thereby close a circuit acrossthe same.

The elevator car 1 is provided with a control switch 12 of any preferred type. In the drawings, there is shown a simple form of four blade, double throw knife switch. Power leads 13 and 14 extend to connection terminals of the control switch 12.

There is also provided a double bar relay 15, the lower bar 16 of which is adapted, when the coil 17 of the relay is de-energized, to contact with terminals 18 and 19 to close a circuit across the same. Likewise, the upper bar 20 of the relay 15'is adapted to contact with terminals 21 and 22 when the coil 17 is de-energized to close a circuit across the same. The terminals 18 and 21 are respectively connected by means of wires 23 and 24 to suitable terminal posts of the control switch 12, and the terminals 19 and 22 are respectively connected by means ofwires! 25 and 26 to the brushes 27 and 28 of the motor which operates the elevator.

One end of the coil 17 of the relay 15 is connected by means of wire 29 to the contact pin 9 hereinbefore described. The other contact pin 8 is connected by means of wire 30 to one of the main power leads 14. The other end of the coil 17 of the relay 15 is connected by means of wire 31 to a terminal 32 of an auxiliary relay 33, the bar 34 of which is adapted, when the coil 35 of said relay 33 is de-energized, to close a circuit across the terminal 32 and another terminal 36. The terminal 36 is connected by means of wire 37 to the main power lead 13.

One end of the coil 35 of relay 33 is con nected by means of wire 38 to wire 25 which extends to one of the brushes of the motor, and the other end of the coil 35 is connected by means of wire 39 to wire 26 which extends to the other brush of the motor.

The "main relay 15 is also provided with terminals 40 and 41, across which a circuit is adapted to be closed when the coil 17 of the relay 15 is energized. The terminal 41 is connected to the wire 29 which extends from the coil 17 to the contact pin 9. The other terminal 41 is connected by wire 42 to one of the terminal posts of the control switch, so that the wire 42 is always supplied with current whenever the control switch 12 is closed to operate the elevator'in either direction.

' The series field windings oil the motor are connected by wires 43 and 44 to suitable terminal posts of the control switch 12. One end of the shunt field windings is connected by wire 45 to a suitable terminal post oi" the control switch 12, and the other end of the shunt field windings is connected by means of wire 46 to wire 44-. I

The operation of the device may now be explained. In the drawings, the various parts are shown in the positions assumed when the elevator is standing still and nn.

loaded. It should be noted that the contact pins 8 and 9 are included in a circuit which is connected to the main power leads in advance of the control switch; Whenever a load in excess of the maximum permissible is placed in the elevator car, the springs 7 will be compressed, whereupon the plate 10 will close the circuit across the contact pins Sand 9.

The current will now flow from power line 14 through wire 30 to contact pin 8, thence through plate 10' to contact pin 9, thence through wire 29 to the coil 17 of the main "clay 15, thence through wire 31 to terminal 32 of the auxiliary relay 33, thence through bar 34 to terminal 36 of relay 33, thence through wirev37 to the other power line 13. Inthis manner, the coil 17 will be energized, raising the solenoid core of the relay, and

thus raising the, bars 16 and 20 from the respective pairs of terminals 18 and 19, and 21 and 22. The lines which extend to the armature brushes of the motor will thus be opened, and when the control switch is closed in either direction, the motor will not be started, for the reasonthat no current will be permitted to flow through the armature.

When, however, the elevator is not overloaded, and the lines extending through the contact pins 8 and 9 to the coil 17 of the relay are open, by reason of the plate 10 not contacting with the pins 8 and 9, the coil 17 will be de-energized and the current will then flow from the control switch 12 through the line 23 to terminal 18 of the relay 15,

thence across the bar 16 to terminal 19 of the rela 15, thence through wire 25 to the brush 2 of the armature, thence through the armatu're and from brush 28 through wire 26 to the terminal 22 of the relay 15, thence through bar 20 to terminal 21 of the relay 15, and thence through wire 24 to the control switch 12.

When the elevator car is carrying a load which is close to the maximum, it will be understood that, due to the inertia ettect u on the starting of the elevator car. the p ate 10 may be brought in contact with the pins 8 and t), and thereby stop the motor through the energization of the coil 17 of the relay 15, and the raising of the bars lti and 20 thereof from their respective terminals. In order to prevent this improper stopping of the motor under such conditions, the anxiliary relay 33 is provided. It will be noted that the coil 35 thereof is connected by means of wires 2-38 and 39 in a shunt 01f the wires 25 and 26 which lead to the motor brushes, so that when the circuit has once been estah lishcd through the armature, the coil, of the relay 33 will be energized, and the bar 34 will thus be raised from the terminals 32 and 36. In this manner, the circuit in which the coil 17 of relay 15 is included will be opened as soon as the circuitto the motor armature is established, and the coil 17 of the relay-15 will be maintained in the deenergized condition notwithstanding that the plate 10 may thereafter be brought to contact with the pins 8 and 9, due to the inertia etlect when the elevator car is carrying a load close to the maximum.

In the operation of the device as hereinbetore described, it is quite likely that the operator, having closed the control switch and finding the car will not start by reason of its overloaded condition, may remove some of the load from the elevator without first opening the control switch, which would result in the accidental starting of the car and might cause serious injury. To prevent the improper starting of the elevator car under such conditions, the main relay 15 is provided with terminals 40 and 41, acro's which a. circuit is adapted to be established by the bar 20 when the coil 17 is in the energized condition. Consequently, when the coil 17 is once properly energized, and the control switch 12 is left closed, the current will flow through line 12 from the control switch 12, to terminal 41, thence through bar 20 to terminal 10, thence through coil 17 to line 31, thence through terminal 32 of relay 33, thence through line 37 to the main power lead 13. Thus the coil 17 will be held in the energized condition until the control switch 12 is opened, which will restore the parts to their initial positions.

It will be seen that there is thus provided a. simple and eflicient device which will automatically prevent the starting of the elevator car in the event that the same is overloaded, which device, however, will not be caused to be improperly operated through inertia effects when the elevator is carrying a load close to the maximum, and which is also provided with means for preventing the improper startingof the elevator in the event that the same is first overloaded and the load afterward reduced below the maximum while the controlling switch is left in the closed or opcrating'condition.

Having thus described the nature and cl'iaracteristic features of my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A safety device for elevators comprising in combination with an elevator car, a switch carried by the car for controlling a motor circuit, power leads extending to the control switch, a motor circuit extending from the control switch, means for opening said motor circuit, and electromagnetic means carried by the elevator for automatically operating said means for opening the motor circuit when the elevator is overloaded.

2. A safety device for elevators comprising in combination with an elevator car, a control switch, power leads extending thereto, a motor circuit extending from the control switch, electromagnetic means for opening said motor circuit, means carried by the elevator for automatically operating said means for opening the motor circuit when the elevator is overloaded, and means for rendering inoperative the means for opening the motor circuit after said motor circuit is closed.

3. A safety device for elevators comprising in combination with an elevator car, a control switch, power leads extending thereto, a motor circuit extending from the control switch, means for opening said motor circuit, means carried by the elevator for automatically operating said means for opening the motor circuit when the elevator is overloaded, and mea s for maintainin the motor circuit open alter the overload 1s removed from the elevator with the control switch closed. 7

4:. A safety device for elevators comprising in combination with-an elevator car, a

control switch, power leads extending thereto, a motor circuit extending from the control switch, means for opening said motor circuit, means carried by the elevator for automatically operating said means for opening the motor circuit when the elevator is overloaded, means for rendering inoperative the means for opening the motor circuit after said motor circuit is closed, and means for maintaining the motor circuit open after the overload is removed from the elevator with the control switch closed.

5. A safety device for elevators comprising in combination with an elevator car, a control switch, power leads extending thereto, a motor circuit extending from the control switch, a main relay adapted when energized to open the motor circuit, a main relay circuit adapted when closed to energize said relay, said main relay circuit being normally open, and means carried by the elevatoiav adapted to close said main relay circuit when the elevator is overloaded.

6. A safety device for elevators comprising in combination with an elevator car. a control switch, power leads extending thcreto, a motor circuit xtending from the control switch, a main relay adapted when energized to open the motor circuit, a main rclay circuit extending from the power leads adapted when closed to energize said relay, said main rclay circuit being normally open, means carried by the elevator adapted to close said main relay circuit when the elevator is overloaded, and means adapted to open the main relay circuit when the motor circuit is closed.

7. A safety device for elevators comprising in combination with an elevator car, a control switch, power leads extending there to, a motor circuit extendingfrom the corn trol switch, a main relay adapted when energized to open the motor circuit, a main relay circuit extending trom the power leads adapted when closed to energize said relay, said main relay circuit being normally open, means carried by the elevator adapted to close said main relay circuit when the elevator is overloaded, an auxiliary relay adapted when energized to open the main relay circuit, and means for energizing said auxiliary relay when the motor circuit is closed. i

8. A safety device forelevatorscomprising in combination with "an elevator car, a control switch, power leads extending thereto, a motor circuit extending from the control switch, a main relay adapted when en ergized to open the motor circuit, a main relay circuit extendinr; from the power leads adapted when closed to energize said relay, said main relay circuit being normally open,- means carried by the elevator adapted to close said main relay circuit when the elevator is overloaded, an auxiliary relay adapted when energized to open the main relay circuit, and a shunt circuit adapted when closed to energize said auxiliary relay.

9. A safety device for elevators comprising in combination with an elevator. car, a control switch, power leads extending thereto, a motor circuit extending from the control switch, a main relay adapted when euergized to open the motor circuit, a main relay circuit extending from the power leads adapted when closed to energize said relay, said main relay circuit being normally open, means carried by the elevator adapted 'to close said main relay circuit when the elevator is overloaded, an auxiliary relay adapted when energized to open the main relay circuit, and a shunt circuit extending from the motor circuit beyond the main relay adapted when closed to energize said auxiliary relay.

10. A. safety device for elevators comprising in combination with an elevator car, a ontrol switch, power leads extending thereto, a motor circuit extending from the control switch, a main relay adapted when energized to open the motor circuit, a main relay circuit extending from the Power leads adapted when closed to energize said relay, said main relay circuit being normally open, means carried by the elevator adapted to close. said main relay circuit when the elevator is overloaded, an auxiliary relay adapted when energized to open the main relay circuit, a shunt circuit extending from the mo tor circuit beyond the main relay adapted when closed to energize said auxiliary relay, means adapted to maintain the main relay energized wl :n the control switch is closed and the main relay circuit is opened after having been closed.

11. A safety device for elevators comprising in combination with an elevator car, a control switch, power leads extending thereto, a motor circuit extending from the. control switch, a main relay adapted when energized to open the motor circuit, a main relay circuit extending from the power leads adapted when closed to energize said relay, said main relay circuit being normally open, means carried by the elevator adapted to close said main relay circuit when the elevator is overloaded, an auxiliary relay adapted when energized to open the main relay circuit, a shunt circuit extending from the motor circuit beyond the main relay adapted when closed to energize said auxiliary relay, and a shunt circuit adapted to be closed when the main relay is energized and the auxiliary relay is tie-energized, said last mentioned shunt circuit being adapted to maintain the main relay energized when the control switch is closed and main relay circuit is opened after having been closed.

In testimony whereof, I have hereunto signed my name.

MORRIS SCHEINFELD.

CERTIFICATE OF CORRECTION.

Patent No. l, 640, 673.

Granted August 30, 1927, to

MORRIS SCHEINFELD.

His hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, line 15, claim I, strike out the word "electromagnetic" and insert the same to follow after the word "switch" in line 14; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 4th day of October, A. D. 1927.

Seal.

M. J. Moore,

Acting Commissioner of Patents. 

